Black spots on underside of Fukien leaves.

[SubJeezy]

Got this Fukien recently. I've been dealing with a Mealy bug infestation, and sooty mold. I've mostly gotten the bugs dealt with, and the mold wipes off easily enough. However, a lot of the leaves have these black spots on the under sides. I understand that it's probably a fungus that affects the flesh of the leaves (?). What fungicides would you recommend to begin to deal the issue? Or is it caused by something completely different that I'm unaware of?

Tree is still in its nursery pot with a interesting mix of soil. Drains fairly quickly but stays moist a while. Outside in full sun. 5a, watered when top inch of soil feels dry. Over a humidity tray (tub with water)

Any and all insights would be greatly appreciated!

 

[SubJeezy]

Bump cause it's lost in the shuffle.

 

[StarJasmine]

Bumping this up again for you! Did you find a solution?

 

[cheap_walmart_art]

Does the black stuff rub off of the leaf cleanly or does it stick and is there necrotic tissue in the middle?

 

[SubJeezy]

Does the black stuff rub off of the leaf cleanly or does it stick and is there necrotic tissue in the middle?

It sticks. Seemed like there was necrotic tissue. I just defoliated the tree to keep the new growth from becoming infected. Has worked well so far.

 

[cheap_walmart_art]

Defoliation of the affected leaves is probably a good idea, plenty of time for it to flush out again. Next time you have something like that though, a good tool would be a jewelers loupe or something similar so you can take a look at the spot. Under magnification you can sometimes see fruiting bodies on the spot, which will indicate fungus. If the spot had a tiny hole in the middle and just dead tissue around, could be the result of pests and in that case fungicide wouldn’t work well. I’ll attach a pdf here with some common ailments and suggested chemical treatments.

 

[SubJeezy]

Defoliation of the affected leaves is probably a good idea, plenty of time for it to flush out again. Next time you have something like that though, a good tool would be a jewelers loupe or something similar so you can take a look at the spot. Under magnification you can sometimes see fruiting bodies on the spot, which will indicate fungus. If the spot had a tiny hole in the middle and just dead tissue around, could be the result of pests and in that case fungicide wouldn’t work well. I’ll attach a pdf here with some common ailments and suggested chemical treatments.

I appreciate it! There were no visible holes. I'm probably going to hit it with an insecticide to just be safe after the fresh growth establishes well. Thanks for the insight!